Product manufacturers often package a plurality of products, sometimes called a product lot, into cases for storage and subsequent shipping to distributors. The quantity of products in the case is often referred to as a case lot quantity. It is not at all unusual during product distribution for a manufacturer or a distributor to break open a case and distribute products in less than case lot quantities. Typically, these products are assembled with other products from other cases pursuant to a shipping order to satisfy individual customer demand.
Filling an order for multiple product types in less than case lot quantities requires that the manufacturer or distributor access the cases for each chosen product type, pick the required number of units of the product from each case, and assemble the picked products into a single container for shipment. This is commonly referred to as broken case order picking. Historically, this task has been manually performed by humans. Manual case picking, however, is a relatively slow process which has proven to be prone to picking errors. Such errors commonly occur when the human operator picks or pulls incorrect products or quantities from the cases to fill the order or forgets to pull a particular product as designated by the order.
Automation of the broken case picking task is the preferred solution to the inefficient and ineffective manual broken case order picking method. A number of automated picking systems, often referred to as automated ordering systems (AOS), are known in the art. In a typical prior art AOS, a terminal operator receives and inputs a product shipping order into the system host computer which typically handles accounting and inventory control functions for the distribution operation. When the order is ready to be executed, a central control computer for the AOS directs in real time the filling of the order by causing the correct products and quantities to be automatically picked and assembled from case lots to complete the order. With such an automated system, the number of incorrectly filled orders and the collateral costs associated with picking errors are minimized or eliminated.
A typical prior art AOS includes a plurality of individual product cartridges stocked with different type of products. The cartridges are arrayed in a matrix configuration along the length of an underlying gathering conveyor belt. Products ejected from the cartridges are collected by the gathering conveyor for transport downstream where the products are output and collected to complete an order according to the input shipping order. An example of a prior art matrix array AOS is shown in FIG. 1 herein and described in commonly assigned, co-pending U.S. patent application Ser. No. 566,530, the disclosure of which is incorporated herein by reference.
To properly collect dispensed products according to the shipping order, the central control computer virtually delineates the gathering conveyor belt into consecutive order zones separated by buffer zones (FIG. 1). The computer, according to the shipping order, then causes the proper products to be ejected from the cartridges onto the conveyor as the order zone assigned to the shipping order by the computer passes thereunder. As each order zone for a shipping order reaches the downstream end of the conveyor belt, the products in the zone are dumped into a shipping container (or tote) for further processing if necessary (for example, manual picking of additional products) and shipment to the customer.
Each product cartridge in an AOS further includes some sort of means for ejecting products from the cartridge onto the moving gathering belt. The combination of an ejector with a cartridge is commonly referred to as a dispenser. Two different means, one passive and the other active, are commonly included in prior art AOS dispensers to eject products onto the conveyor belt. The passive and active ejection systems for an AOS are typically distinguished from each other by the actions taken on the product by the ejection mechanism. An active system can usually be distinguished from a passive system in that active systems include means for forcibly ejecting the product from the dispenser cartridge.
For example, a passive gravity assist product release system is shown in FIGS. 5A and 5B of commonly assigned, co-pending U.S. patent application Ser. No. 566,530. This passive system includes a dispensing gate at the end of the product cartridge and a stop gate positioned within the cartridge at least one product length from the dispensing gate. The two gates are configured such that while one is closed the other is open, and vice versa, thereby allowing products in the cartridge to be singularly dispensed. When the dispenser gate opens, the bottom-most product in the stack is released. When the stop gate opens, the next product advances down the cartridge into position to be released the next time the dispense gate is opened. This passive system advantageously utilizes the force of gravity, rather than use a forcible ejector, to deposit the products released by the dispense gate onto the underlying conveyor.
An example of a prior art active lever eject system is shown in FIGS. 5-7 of U.S. Pat. No. 4,518,302, issued to Knapp. A lever is positioned for rotation about an axis such that one end of the lever is adjacent to the edge of the bottom-most product in the cartridge. An actuator, coupled to the lever, causes the lever to rotate about the axis forcing the end of the lever adjacent to the product to eject the product from the cartridge. This active system, as can be seen, differs from the passive system in the use of the lever as an ejector or kicker to apply force on the edge of the bottom product to eject the product from the dispensing cartridge onto the underlying conveyor.
Many prior art passive and active ejection systems and mechanisms share several shortcomings which render their continued use undesirable. For example, due to the configuration of the ejection system, the actuator (solenoid, hydraulic, pneumatic, etc.) and the associated mechanism tend to occupy a significant amount of space in the system, especially in the downstream conveyor direction. This adversely affects the ability to expand the capacity of the system when given a conveyor of limited, fixed length, as the space needed for additional product cartridges in the expanded system is occupied by the inefficiently designed actuators and mechanisms for the existing dispensers in the matrix.
An additional shortcoming experienced with prior art passive and active ejection systems is damage to the dispensed products as the products are ejected from the cartridge and impact with the underlying moving conveyor. In the passive system, the product free-falls in a vertical direction to land on the conveyor moving in a horizontal direction. In the active system, the products are often ejected in downward direction and typically opposite to the conveyor flow, or downward and laterally across the flow of the conveyor. The acute impact between the moving conveyor and product in both passive and active systems has proven to be a significant factor in dislodging products from their packaging and causing damage to products and their packaging.
Furthermore, the ejection systems of the prior art have proven to have built-in limitations in their ability to handle products of different sizes and shapes. Earlier passive systems utilize friction between a product and a dispenser stop gate to retain the product during release of the bottom-most product. Thus, flat or thin packages must be stacked lengthwise rather than flat in the dispenser as the thin edge of the package when stacked flat does not provide enough of a surface for the stop gate to hold the product in the cartridge. This reduces the number of products that may be placed within a cartridge necessitating frequent refilling thereof. Furthermore, if improperly stacked, a single actuation of the ejector may cause two or more products to be ejected.
Accordingly, there is a need for an improved means for ejecting products from a product cartridge onto a moving conveyor belt in an automated order system having a plurality of product dispensers. In order to maximize the number of dispensers that are positionable along the longitudinal length of the conveyor, the actuation mechanism and ejection mechanism (ejector) should be as longitudinally thin as possible in order to more closely stack adjacent dispensers in the matrix. Furthermore, the means should provide efficient and reliable dispensing with minimal resultant damage to either the product or package. Finally, the means should be adjustable to handle various sizes and shapes of products.